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Analysis of treating solid waste by pyrolysis and gasification based on building green airports
Published in Binoy K. Saikia, Advances in Applied Chemistry and Industrial Catalysis, 2022
Bo Li, Boyu Zou, Jixiang Su, Ran Lei
This technology first cracks waste into small-molecule combustible gas and then burns them at high temperature in the second combustion chamber, avoiding toxic gases such as dioxins commonly produced by direct waste incineration. The heat generated by the combustion in the second combustion chamber can be recycled to motivate the system, and waste heat can be utilized for power generation, heating, etc. In this way, waste becomes a renewable resource. The organic waste is reduced by more than 90%, and almost no fly ash is produced. The discharged slag can be further used as resources or sent to domestic waste landfills.
Introduction
Published in Kushal Ghosh, Partha Ghosh, Alkali-Activated Fly Ash Blast Furnace Slag Composites, 2020
Slag is a by-product created from the manufacturing process of different types of metals. Slag is composed mostly of oxides of alumina, silicates, calcium, and magnesium. Slag is widely used in the concrete industry as a supplementary cementitious material. The specific type of slag used for concreting is obtained from the steel and iron industries and is known as blast furnace slag. Blast furnace slag is generally formed by suddenly cooling the molten slag by immersing it in water. This action alters the molten slag into particles with size less than 4 mm. These particles are largely made of amorphous compounds as sudden cooling does not allow complete crystallization to take place. As slag is rich in calcium and aluminum, it demonstrates good binding properties on reaction with an alkaline medium. The behavior of slag depends on the raw materials being used to manufacture the required metal. The variation in raw materials affects the behavior of slag when subjected to alkali activation. Therefore, it is preferable to perform multiple trial mixes before using the slag for large-scale applications.
Recovery of Value-Added Materials from Iron Ore Waste and Steel Processing Slags with Zero-Waste Approach and Life Cycle Assessment
Published in Hossain Md Anawar, Vladimir Strezov, Abhilash, Sustainable and Economic Waste Management, 2019
Hossain Md Anawar, Vladimir Strezov
The Fe-mineral ores contain impurities of phosphorus, sulphur and high alkali, as well as impregnations of waste rock. The magnetic separation of iron minerals and washing iron ores leaves the tailings and wastewater, consisting mostly of silicate rock and clay that are not expected to be hazardous (US EPA, 1988). During iron making, iron ore, coke, heated air and limestone or other fluxes are fed into a blast furnace. Blast furnace slag contains oxides of iron, silicon, aluminum, calcium, magnesium and manganese, along with other trace elements. There are three types of blast furnace slag: air-cooled, granulated, and pelletised (or expanded) (US EPA, 1990). Blast furnace slag should normally be generated at a rate of less than 320 kg/t of iron, with a target of 180 kg/t. The impurities in the feed materials control the generation of blast furnace slag. Cokeless iron making procedures are currently being studied and, in some places, implemented such as the Japanese Direct Iron Ore Smelting (DIOS) process that produces molten iron from coal and previously melted ores (USEPA, 1995). This process has the effect of cutting the costs of molten iron production by about 10% and reducing emissions of carbon dioxide by 5–10% (Furukawa, 1994).
Direct smelting process of copper carbonate ore using SiO2 as fluxing agent in electric arc furnace
Published in Canadian Metallurgical Quarterly, 2023
Fakhreza Abdul, Muhammad Ikhwan Rahman, Yuli Setiyorini, Vuri Ayu Setyowati, Sungging Pintowantoro
Most smelting processes will produce slag as another by-product of the molten metal. Slag is a collection of gangue minerals from all ingredients included during the smelting process. The slag’s nature will determine the smelting process’s success and smoothness. The addition of SiO2 flux will modify the properties of the slag. So, the expected slag properties, such as having the lowest possible melting temperature, having the desired mineral compound, and having a low viscosity, can be obtained. The addition of SiO2 flux can affect losses and Cu content in the slag. Figure 7(a) and (b) shows the Cu content and other constituent composition in the slag, along with the addition of SiO2 in the smelting process. The slag mass was 26, 24, 25, 29, and 24 g for 0–8 wt% of SiO2 addition, respectively. The Cu content in this study was in the range of 0.68–1.64%. It is still in the range of typical Cu content in copper slag, which is between 0.2 and 2.1% [30].
Study of the effect of pozzolanic Portland cement-basic oxygen furnace slag on the mechanical properties of roller compacted concrete
Published in International Journal of Pavement Engineering, 2022
Two types of slag available include Blast Furnace Slag (BFS) and Basic Oxygen Furnace Slag (BOFS). Iran's cement industry consumes almost all quantities of BFS. In addition, to use BFS as an aggregate, the crusher and then the sieves must be used for their gradation. In this case (use of BFS), the economic aspect of slag consumption is strengthened while the cost of producing concrete with slag is enhanced. But BOFS does not need a crusher and just needs gradation like other aggregates. Therefore, in addition to the environmental aspect, they are also considered from the economic aspect. BOFS, which have the good abrasion resistance and high shear strength, have a sharp corner shape, rough surface, and high specific gravity. Also, their pH varies between 8 and 10. It should be noted that the presence of FL and magnesium oxide in BOFS that have not reacted with silicate compounds in the production process leads to that the BOFS can be hydrated in humid environments and is increased in volume by up to 10%. Before consuming these materials, BOFS should be exposed to moisture and rain for several months to eliminate their potential to enhance its volume (Responsible for Regional Development Steelmaking 2009, Turner Fairbank Highway Research Center 2002, U.S. Geological Survey U.S. Department of the Interior 2016, ASTM International 2012).
Phosphorus removal from wastewater using electric arc furnace slag aggregate
Published in Environmental Technology, 2022
Mingwei Liu, Xiao Liu, Weizhuo Wang, Jingbo Guo
Steel slag is a typical industrial metallurgical by-product. As the biggest steel producer and consumer country, China’s annual output of crude steel was more than billion tons over the past three years and the annual generation of steel slag also exceeded 100 million tons [13]. The slag is mainly recycled for cement and concrete production, road construction, civil engineering work. However, the steel slag contains a large number of free-CaO and free-MgO, which will result in volumetric instability when used in road or civil engineering projects, thus limiting its large-scale application [14,15]. So far, more than 300 million tons of steel slag cannot be completely consumed and have been deposited in China. Therefore, it is imperative to develop alternative technologies to recycle and manage steel slag.